I came across this while search the web for you.. will probably help.. same idea Tom had but a little more detailed...
If you are having problems with:
1st gear - Adjust the shifter back
1st and 2nd - Adjust the shifter to the right
2nd gear - Adjust the shifter forward
1st and 3rd - Adjust the shifter adjust to the back
2nd and 4th - Adjust to the front
3rd - Adjust back
3rd and 4th - Adjust left
4th - Adjust forward
Reverse: adjust the shifter right or front; but just a little. Reverse could be an internal transmission problem.